3 files changed, 18 insertions, 6 deletions

diff --git a/src/math/twists.c b/src/math/twists.c
index 3f1296d..043594f 100644
--- a/src/math/twists.c
+++ b/src/math/twists.c
@@ -13,16 +13,25 @@ void twist_rand_to(curve_t *to, const curve_t *of) {
 	if (typ(of->field) == t_INT) {
 		to->a = ell_get_a4(to->curve);
 		to->b = ell_get_a6(to->curve);
+		if (of->order != NULL) {
+			GEN q = addis(mulis(of->field, 2), 2);
+			to->order = subii(q, of->order);
+			obj_insert_shallow(to->curve, 1, to->order);
+		}
 	} else if (typ(of->field) == t_FFELT) {
 		to->a = ell_get_a2(to->curve);
 		to->b = ell_get_a6(to->curve);
+		if (of->order != NULL) {
+			GEN q = addis(mulis(int2n(degree(FF_mod(of->field))), 2), 2);
+			to->order = subii(q, of->order);
+			obj_insert_shallow(to->curve, 1, to->order);
+		}
 	}
 }
 
 void twist_rand(curve_t *what) {
 	twist_rand_to(what, what);
 	seed_free(&what->seed);
-	what->order = NULL;
 	points_free_deep(&what->points, what->npoints);
 	points_free_deep(&what->generators, what->ngens);
 }
\ No newline at end of file
diff --git a/src/math/twists.h b/src/math/twists.h
index dcbdb31..d68bb27 100644
--- a/src/math/twists.h
+++ b/src/math/twists.h
@@ -15,8 +15,8 @@
 void twist_rand_to(curve_t *to, const curve_t *of);
 
 /**
- * @brief
- * @param what
+ * @brief Twists the <code>what</code> curve randomly, inplae.
+ * @param what The curve to be twisted, also the result.
  */
 void twist_rand(curve_t *what);
 
diff --git a/test/src/math/test_twists.c b/test/src/math/test_twists.c
index 8a869bf..cc39369 100644
--- a/test/src/math/test_twists.c
+++ b/test/src/math/test_twists.c
@@ -4,7 +4,6 @@
  */
 #include <criterion/criterion.h>
 #include "gen/field.h"
-#include "gen/point.h"
 #include "math/poly.h"
 #include "math/twists.h"
 #include "test/default.h"
@@ -19,7 +18,8 @@ Test(twists, test_twist_rand_to_fp) {
 	curve_t curve = {.a = a,
 	                 .b = b,
 	                 .field = stoi(23),
-	                 .curve = ellinit(mkvec2(a, b), stoi(23), -1)};
+	                 .curve = ellinit(mkvec2(a, b), stoi(23), -1),
+	                 .order = stoi(24)};
 
 	curve_t to = {0};
 	twist_rand_to(&to, &curve);
@@ -27,6 +27,7 @@ Test(twists, test_twist_rand_to_fp) {
 	cr_assert_not_null(to.b, );
 	cr_assert_not_null(to.field, );
 	cr_assert_not_null(to.curve, );
+	cr_assert(equalii(to.order, stoi(24)), );
 }
 
 Test(twists, test_twist_rand_to_f2m) {
@@ -38,7 +39,8 @@ Test(twists, test_twist_rand_to_f2m) {
 	    .a = a,
 	    .b = b,
 	    .field = field,
-	    .curve = ellinit(mkvecn(5, gen_1, a, gen_0, gen_0, b), NULL, -1)};
+	    .curve = ellinit(mkvecn(5, gen_1, a, gen_0, gen_0, b), NULL, -1),
+	    .order = stoi(8140)};
 
 	curve_t to = {0};
 	twist_rand_to(&to, &curve);
@@ -46,4 +48,5 @@ Test(twists, test_twist_rand_to_f2m) {
 	cr_assert_not_null(to.b, );
 	cr_assert_not_null(to.field, );
 	cr_assert_not_null(to.curve, );
+	cr_assert(equalii(to.order, stoi(8246)), );
 }
\ No newline at end of file